The invention relates to plant propagation systems, and more particularly to propagation systems and apparatus that reduce heat generated by light that is directed upon plants which are located in a growing space.
Tissue culture propagation, sometimes referred to as micro propagation, is the process of growing plants from a piece of plant tissue that has been extracted from a parent plant. Horticulturists favor plant propagation as a growing method because its provides relatively high production efficiency and greater uniformity of plants. The process results in mass production of plants having certain desirable characteristics because substantially all the plants produced are genetically identical to and have all the desirable traits of the parent plant.
Plant propagation may be described as subdivided into stages. Stage one is sometimes said to comprise initiation, in which a plant shoot or bulb is initiated in a growing media. Stage two comprises a multiplication phase in which nutrients and hormones are provided to enable rapid cell division and substantial growth of the plant. In stage two, it is very important to keep pathogens and biological pests from harming the plant. In stage three, the plant is moved out of the laboratory environment and into a greenhouse, where the plant may begin to take on larger amounts of heat and light, developing roots that will be needed for transfer to the field in the natural environment outdoors. It is important to avoid subjecting the entire crop or field to biological pests, and one way to accomplish that result is to propagate the plants in an environment that shields the maturing plant from pathogens, while also facilitating rapid and vigorous growth. Sometimes, a fourth stage is employed to form a root on the shoot, thereby completing development of a whole plant.
Apparatus and methods have been devised to micro propagate plants in the above referenced manner. For example, U.S. Pat. Nos. 5,525,505 (the xe2x80x9c""505 patent) and 5,597,731 are directed to plant propagation systems that use sealed vessels. Such systems employ chambers that have been sold commercially as Acclimatron(trademark) vessels (xe2x80x9cAcclimatronxe2x80x9d is a trademark of the Southern Sun Company). These two referenced patents disclose sealed, semipermeable membrane vessels for completely enclosing plant material therein. The sealed vessels typically are translucent and permeable to gases and liquids while remaining impermeable to biological contaminates. Plant tissue extracted from a parent plant may be placed within the sealed vessels and grown heterotrophically. Once it develops, the plant may be transferred to a greenhouse environment for photoautotrophic growth. In the greenhouse environment, the sealed vessels are supported in trays, and exposed to light, gases, water, and a liquid nutrient solution for optimizing growth.
In the ""505 patent, FIG. 5 shows a spectral filter designed to contain a colorized liquid for filtering light. See column 10, lines 37-68 of the ""505 patent. The filter is said to include channelized glazing extending in between an intake chamber and an exit chamber. The patent references that colorized liquid may be added to the spectral filter. The spectral filter can be used to control temperatures within the vessel support tray, to prevent the plant material within the sealed vessels from becoming overheated. A spectral filter of the type shown in the ""505 patent is sometimes called a water jacket panel. In general, they rely upon shading from the spectral filter to provide a cooling effect. Furthermore, they may employ conventional cooling mechanisms of growth chamber water jackets.
Unfortunately, even devices as shown in the ""505 patent still cannot meet all the needs of plant growers. Sealed vessels are expensive and costly to use as a growing medium for plants on a commercial scale that must be produced very cheaply. Furthermore, heat generated by light impacting a chamber is very intense in summer growing seasons, and spectral filters sometimes cannot adequately carry away heat to ensure that plants are shielded from damaging heat. Thus, growth of plants is limited under such conditions.
What is needed in the plant propagation industry is a method and apparatus for producing plants to facilitate a more efficient cooling effect upon the growing space where the plants are located in the chamber. An apparatus that is capable of circulating a cooling fluid in a more efficient manner to take advantage of the physics of radiation from a black body would be desirable. Furthermore, a top panel or lid system that can more efficiently cool plants, and provide for better and faster growth, at less cost, would be highly desirable.
The present invention recognizes and addresses the foregoing disadvantages, and others of prior art constructions, and methods.
Accordingly, it is an object of the present invention to provide a plant propagation system.
It is another object of the present invention to provide a new apparatus and system for propagating plant material.
It is a further object of the present invention to provide a plant propagation system and method that does not rely upon conventional cooling mechanisms, and instead employs an infrared heat sink.
It is another object of the present invention to provide a plant propagation system and method that prevents contamination of the growing plant material.
It is another object of the present invention to provide a plant propagation system and method that reduces substantially heat, to provide a temperature in the growing space that is conducive for plant growth.
It is a further object of the present invention to employ an apparatus for cooling plant containers during growth using a flow regime and direction that accommodates utilizes black body radiation, convective air movement for better control of leaf temperature.
The invention comprises a system and apparatus for growing plants. The system includes a first thermal panel with at least two flow channels. A thermal panel is located between a growing space and a light source. A cooling fluid is circulated in a countercurrent flow pattern (i.e. in at least two different directions). The channels may be connected to one or more headers, which serve as fluid manifolds to deliver fluid, and to collect fluid, from the flow channels. Growing closely spaced plants from seed or cuttings to transplants for the field or a greenhouse is one application of the system. Transplants increase their economic value when their vegetative or reproductive responses are appropriately regulated. In general, the system can minimize energy and material consumption while, at the same time, optimizing photosynthetic and photomorphogenic characteristics in the plants.
The system also optionally may provide that the first thermal panel is subdivided into a plurality of channels. The system may provide at least a first channel and a second channel substantially parallel to each other. The system, in one embodiment, may include a cooling fluid that flows in a first direction in the first channel, and in a second direction in the second channel. The first direction and second direction are essentially opposed to each other.
The system optionally may include a third channel and a fourth channel, the third channel lying adjacent the second channel and the fourth channel lying adjacent the third channel. In that way, the first, second, third, and fourth channels are aligned substantially parallel to each other.
The system optionally may provide for a flow direction along the third channel that is in the first direction. Further, the flow direction along the fourth channel is in the second direction. In that way, the flow direction in respective channels alternates from the first direction to the second direction in successive channels.
The system also may include a first thermal panel providing a heat sink so that a significant portion of heat generated from radiation transmitted into the first thermal panel is absorbed and transferred away and out of the first thermal panel by the cooling fluid. The cooling fluid may consist essentially of water, or may optionally consist of ethylene glycol, or any other fluid that efficiently and effectively transfers heat in an efficient and economical manner.
The plants grown in the system further may include photoreceptor sites upon their leaves, so that a leaf surface may act as a heat source within the growth chamber due to the absorption of light. The first thermal panel includes an upper and a lower surface. The average temperature difference between photoreceptor sites and the lower surface of the first thermal panel is at least 20 degrees C. The system of claim 1 also provides a second thermal panel so that the plants are located between the first thermal panel and the second thermal panel.